1. Field of the Invention
This invention relates to a method of manufacturing a semiconductor device.
2. Description of the Related Art
In the process for forming a dual damascene wiring structure of a semiconductor integrated circuit device, it is required to planarize an organic film employed as an underlying film. The planarization of the organic film has been conventionally employed for the via-first formation or so-called via-first in a dual damascene process wherein a trench pattern is formed after the formation of a hole pattern (via-hole pattern).
As described in JP-A 2004-363191 (KOKAI) for example, in the planarization of an organic film according to this process, a slurry containing resin particles is employed, for example. According to this process, the magnitude of dishing can be inhibited by regulating the size of resin particles to a range larger than the diameter of a hole.
Further, in viewpoint of the controllability of working and shaping, it is considered more advantageous to employ a hybrid-type interlayer insulating film structure. In the case of the hybrid dual damascene process, there has been mainly adopted a dual damascene process of the so-called trench mask-first, wherein a hard mask is worked so as to form a wiring trench.
In the working process of the trench mask-first, for the purpose of forming a wiring trench and a connecting hole by a hard mask consisting of a plurality of layers, there has been proposed, as seen in JP-A 2006-019690 (KOKAI) for example, to form an underlying film, and then the surface of the underlying film is planarized by a CMP method. In this process, an organic film is formed on the hard mask having a wiring trench formed therein, by coating and then baking at a high temperature exceeding the cross-linking temperature thereof to form a film which is high in hardness. Subsequently, this hard organic film is removed by CMP using alumina particles, thereby inhibiting the magnitude of dishing.
However, this working process is accompanied with a problem that a deep scratch that may damage the hard mask may generate due to the alumina particles. The reason is that alumina particles are the highest in hardness of abrasive grains. Further, when alumina particles are left after the polishing of the organic film, they may act as an etching mask in a subsequent working process. As a result, an abnormal configuration may generate in the worked wirings, thus decreasing the yield of wirings.